Herpes simplex virus types 1 and 2 (HSV1 and HSV2) are infectious agents, and their association with cancer occurrence in human is a controversial topic for decades. We addressed this subject using all available continuous National Health and Nutrition Examination Survey (NHANES) cross-sectional data from 1999 to 2014.
Li and Wen BMC Cancer (2017) 17:726 DOI 10.1186/s12885-017-3734-2 RESEARCH ARTICLE Open Access Seropositivity to herpes simplex virus type 2, but not type is associated with cervical cancer: NHANES (1999–2014) Sen Li1,2* and Xi Wen3 Abstract Background: Herpes simplex virus types and (HSV1 and HSV2) are infectious agents, and their association with cancer occurrence in human is a controversial topic for decades We addressed this subject using all available continuous National Health and Nutrition Examination Survey (NHANES) cross-sectional data from 1999 to 2014 Methods: Eight data cycles (1999–2000, 2001–2002, 2003–2004, 2005–2006, 2007–2008, 2009–2010, 2011–2012, and 2013–2014) were employed, and a sample of 8184 female participants was used in this study according to the availability of cancer history and HSV serostatus Results: The seroprevalences of HSV1 and HSV2 were 60.73 ± 0.89 and 25.02 ± 0.64, respectively, and the numbers increased with age (P < 0.01) In confounder-adjusted logistic regression analysis, association between HSV1 seropositivity and uterine cancer was identified (adjusted odds ratio-ORadjusted = 6.03; 95% CI: 1.52, 23.87) HSV2 seropositivity was associated with cancer occurrence (ORadjusted = 1.47; 95% CI: 1.01, 2.14), cervical cancer (ORadjusted = 1.72; 95% CI: 1.06, 79) and uterine cancer (ORadjusted = 3.49; 95% CI: 1.03, 11.85) Moreover, HSV2 was persistently associated with cervical cancer after further adjusting high-risk human papillomavirus (HPV) as confounder (ORadjusted = 1.90; 95% CI: 1.09, 3.34) Relative risk (RR)-based interaction measurement between HSV2 and HPV on the additive scale suggests higher RR for cervical cancer in participants with seropositivity for HPV only (RRadjusted = 2.98; 95% CI: 1.23, 7.20; P = 0.02), HSV2 only (RRadjusted = 2.79; 95% CI: 1.31, 5.96; P = 0.01) or both viruses (RRadjusted = 3.44; 95% CI: 1.50, 7.86; P < 0.01) when setting participants with seronegativity for both HPV and HSV2 as reference Conclusions: The finding of current study provides epidemiological evidence that serostatus of HSV2 can serve as an independent predictor for cervical cancer Keywords: Cervical cancer, HSV, HPV, NHANES Background Cervical cancer represents the fourth most common cancer among women globally: It accounts for 7.9% of total cancer cases in females 528,000 newly occurred cases and 266,000 deaths were estimated in 2012 [1, 2] In the United States, the estimated cervical cancerrelated emerging cases and deaths are 12,990 and 4120, respectively, in 2016 [3] Cervical cancer mainly affects countries with low or medium levels of human * Correspondence: senli@bucm.edu.cn School of Life Sciences, Beijing University of Chinese Medicine, Beijing, China Department of Physiology, LKS Faculty of Medicine, University of Hong Kong, Hong Kong, China Full list of author information is available at the end of the article development, and its incidence rates vary significantly from country to country with a range of 3.8/100,000 in Israel to 48.2/100,000 in Colombia for each year [4] Early changes in cervix (e.g squamous intraepithelial lesions) can be detected years before malignancy by screening tests like Pap smear, and such primary screening has resulted in declined incidences of cervical cancer in several countries over the past 30 years Due to its characteristics of being sexually transmitted, cervical cancer is deemed as sexually transmitted cancer [5] Indeed, recent changes in sexual behavior have led to increase in risk of HPV infection, thereby elevating cervical cancer incidences in several eastern European countries and former Soviet states [1] © The Author(s) 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated Li and Wen BMC Cancer (2017) 17:726 Individuals with HSV1 or HSV2 infection become lifelong carriers In 2005–2010, the seroprevalences of HSV1 and were 53.9% and 15.7%, respectively, among 14- to 49-year-olds in the United States [6] As characterized by oral-labial lesions, HSV1 infection is generally transmitted nonsexually while HSV2, as one of the most common sexually transmitted diseases (STDs), is predominantly transmitted from sexual partner with unrecognized or asymptomatic disease Because of its role in facilitating HIV acquisition and transmission, prevalence and epidemiology of HSV2 have been more frequently described than that of HSV1 [6] However, it is of note that HSV1 can also be a significant cause of genital herpes in individuals with oral-genital contact [7] Despite many decades of investigation, the question whether cervical cancer can be induced by herpes viruses is still in debate HSV2 was hypothesized to be the cervical cancer-inducing sexually-transmitted factor even earlier than HPV [4, 5]: higher rates of HSV2 antibodies have been found in patients with cervical cancer compared to control as early as the second half of twentieth Century [8–10] However, this opinion has been weakened by some of the epidemiologic studies, along with the lack of detection of HSV2 DNA in cervical tissues [11] Thus, the proposed aetiological link between HSV2 and cervical carcinoma remains unproved [12] On the other hand, HSV1 is capable of interfering with DNA repairing and inducing genetic modifications in acute lymphoblastic leukemia [13] Moreover, HSV1 is found to play a role in thyroid carcinogenesis [14] To address this subject of an active controversy, current study was performed using the NHANES data with following specific aims: 1) to examine whether HSV1 and were independent risk factors for occurrence of any or femalespecific types of cancer, and 2) to evaluate the combined effect of HSV2 and high-risk HPV seropositivity for the development of cervical cancer, and possible interaction between HSV2 and HPV in cervical carcinogenesis Page of HSV1 or HSV2 measurement, a total 12,116 females had HSV serostatus In this population, subjects who lacked information on whether having cancer (n = 1545) or failed to provide specific cancer type (n = 7) were also excluded, leaving 10,564 female participants, aged 20 years or older, with cancer status Next, participants with insufficient information on other variables (n = 1949) or received HPV vaccination (n = 431) were also removed, leading to a final study population of 8184 females (Additional file 1: Figure S1) For HPV-related analysis, only four data-cycles (2003–2010) were employed due to the availability of serum HPV test, and 4298 female participants were included in the analyses HSV and HPV serostatus Blood samples were collected from eligible subjects at mobile examination center, and shipped to Emory University or CDC for HSV or HPV analysis, respectively Serostatus of HSV1 and HSV2 were accessed by solid-phase enzymatic immunodot assay using virus type-specific purified glycoprotein as antigen, and the outcomes were categorized as positive, negative and indeterminate Competitive Multiplexed Luminex Assay was employed to determine HPV serostatus by simultaneously measuring antibodies against HPV-16 and -18 Readouts of this assay were quantitative, and were presented as arbitrary units (milliMerck units/ml) Threshold for positive results were defined to generate qualitative results (positive-at or above threshold; negative-below threshold) for HPV-16 and -18 Multiplexing the assay has little to no effect on the simplex standard curves for HPV-16 and -18 (the only two types of HPV, as high-risk HPV types, that have been employed in current work), revealing limited crossreactivity [16] The detailed methodology is available in the NHANES laboratory procedure manual [17] For analytic purpose, four additional variables were created: seropositivity for HSV1 or HSV2, both HSV1 and HSV2, HPV (types 16 or 18, as high-risk HPV types), and both HPV and HSV2 Methods Study population Cancer status Continuous NHANES is a population-based nationwide complex survey to collect and evaluate health and nutrition condition of the non-institutional civilian U.S population [15] The survey data is released by U.S National Centers for Health Statistics (NCHS) biannually for public use since 1999, and NHANES has been approved by National Health Statistics Institutional Review Board In this study, data from all eight available survey cycles (1999–2014) were employed, which contains a total of 39,755 U.S female participants Status of HSV1 and HSV2 infection were measured in the 14–49 years old subgroup in each data-cycle After excluding subjects with missing (n = 27,566) or indeterminate (n = 73) Cancer status was judged based on answers to the question “Have you ever been told by a doctor or other health professional that you had cancer or a malignancy of any kind?” and its subsequent question “What kind of cancer was it?” in medical condition questionnaire Occurrence of any type of cancer (any cancer) and four specific female-related cancers were present in this study Other variables The associations between status of cancer and HSV/ HPV seropositivity were adjusted for a series of potential confounding factors: age (20–29, 30–39 or 40–49), race/ ethnicity (Non-Hispanic white, Non-Hispanic black or Li and Wen BMC Cancer (2017) 17:726 others), education (high school), poverty income ratio (PIR; median, where medians were computed based on PIR ≥1 for each of the eight data cycles), body mass index (BMI;